Do you think you know what really happened after World War II? You don't. Sigma made sure of that.

American investment banker Ben Hartman arrives in Zurich, the first time he's been back to Switzerland since his twin brother died there in a tragic accident four years ago. But when Ben chances upon Jimmy Cavanaugh, an old college friend, Cavanaugh draws a gun and tries to kill him. In minutes, several innocent bystanders are dead, as well as Cavanaugh, and Ben is on the run, plunged into an unspeakable nightmare.

U.S. Department of Justice field agent Anna Navarro is being stalked by a relentless killer, managing to survive only by a combination of luck, skill, and her own quick wits. The attacks on her are somehow related to her current assignment: investigating the sudden, seemingly unrelated deaths of a number of very old men around the world. The only thing that connects them is an ancient CIA file bearing the code word Sigma.

Brought together by accident, Ben and Anna realize that their only hope of survival lies with each other. Together they race to uncover the long-hidden diabolical secrets of Sigma - secrets that threaten everything they think they know, everything they believed about their friends and families, everything they were taught about history itself. For behind Sigma lies a vast deception that is finally coming to fruition - and the fate of the world is in their hands. Download and start listening now!

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Listener Opinions

by Jodi-Kay Lofters | 2/16/2014

" Read October - Nov 2012 "

by Jeff Mayo | 2/10/2014

" One of Ludlum's better books outside of the Bourne series. This one involves an investment banker who is thrown suddenly and violently into an international banking scandal. The plot involves big businesses with big secrets that they are willing to kill to protect. Laundered Nazi money leads a trail around the world. And while those familiar with Ludlum will have the basic plot figured out long before they read it, getting there is half the fun in this fast paced adventure. "

by Sue Boros | 2/9/2014

" two stories meet up and the action doesn't stop. Definitely a five star book "

by Kenyon Harbison | 2/4/2014

" A fast-paced, enjoyable, but cookie-cutter and simplistic thriller novel by the author of the "Bourne" series. Two plotlines intertwine, that of Ben Hartman (a handsome, tall, sophisticated, rich financial manager) and Anna Navarro (a smart, beautiful, independent-minded federal agent). Intrigue piles on intrigue. Surprise piles on surprise. Sympathetic supporting characters get killed. The two main characters are very often nearly, but never actually, killed. Etc., etc., etc.... The central conspiracy surrounds a secret corporation, composed of rich, powerful people, founded after WWII to promote capitalism, which now may or may not have fallen into nefarious hands, and which is now trying to kill Ben and Anna (who, incidentally, naturally eventually fall for one another about 2/3 of the way through the book). Believe me, that's no spoiler, you'll see it coming. You'll see a lot coming. Good airplane reading though. "

" Liked it. Fast-paced and very interesting. I'd like to see it made into a movie. I love the European backdrop and the plot is intriguing. The characters were mostly good, but sometimes unrealistic. "

Ryan Mishap | 1/20/2014

" I won't review all of his books as that would be pointless. These are like TV for me, but that isn't to say some aren't worthwhile. Ludlum successfully transitioned from doing spy books about the commies and the Nazis after the end of the cold war. Who were to be the new villains? Why, corporations of course. These later books usually involved people who weren't super-spies or ex-military, but "ordinary" (rich) guys who stumble on to some plot and have to figure it out while on the run from professional assassins. Fun stuff! "

Marc | 1/12/2014

" Well-written, but a little too far-fetched for my taste. I like adventure books with secret societies and lots of twists and turns in the plot, but the sheer scope of the suspension of disbelief required for the overall premise detracts from the enjoyment I received. "

Amy | 1/11/2014

" I'm a big fan of the Bourne series movies, but had never read anything by Robert Ludlum until The Sigma Protocol. This was a great book...really suspenseful and I didn't see the ending coming! This would make a great movie and I was doing the casting for it in my head the entire time I was reading the book. This definitely made me want to read some more of Ludlum's work. "

Kieryn Nicolas | 1/6/2014

" What an intense plot! I could hardly turn the pages fast enough. I also loved the characters :) "

Sarah | 1/6/2014

" An intriguing story and very suspenseful, but I like other Ludlum novels better. "

Paul | 12/28/2013

" Entertaining book...good suspense and well-crafted characters that you can care about. "

Darryl Stangry | 12/26/2013

" Good fiction that doesn't get out of date with age. "

Mandy | 11/28/2013

" Loved this book, if you like the Borne Series you'll love this "

James | 11/24/2013

" Fun book........Wasn't terribly surprised by the plot climax, but the buildup was fun and exciting. "

Jelan | 11/24/2013

" This is a typical, enjoyable Ludlum book... an escapist page-turner. The premise was fairly far-fetched, but I enjoyed every page nonetheless. I'm always happy to discover a Ludlum I haven't read yet when I'm in need of a mental break. "

Carrie | 11/15/2013

" Really long and a bit slow at times but the parts that were good well, were really good! Took me a while to get through this one though. "

Dj | 11/11/2013

" The description says it all. Read it and then the book if the description strikes that curiosity cord that us readers have come to use to define our genre preference. "

Nick | 4/17/2013

" having a hard time putting this down... "

Rhod | 4/15/2013

" Kept me on the edge of my seat - so to speak. Good, tight mystery adventure with danger at every turn. "

David H. | 2/9/2013

" I am surprised that I didn't discover Ludlum earlier. Having seen all the Bourne movies, it seems like I would of read his novels sooner. Afterall, I have always enjoyed spy stories. One day, I plan of reading those 3 Bourne novels "

Dhiratara | 2/4/2013

" This book is older than Da Vinci Code and all rows of Dan Brown's work. But I suggest you to read this after you learn the basic subject of conspiracy thingy in Da Vinci Code, Angels and Demons, The Holy Grail, etc. It's shocking, electrifying, mesmerizing! "

Deb | 1/23/2013

" Read many of Ludlum's enjoyable books in high school in the 70s. Page turners. "

" Very much enjoyed the fast pace of this one. One thing I have to say is that it would be very convenient to be super rich when on the run from crazy assasins - I don't know how a poor person would've been able to jump from country to country like this. "

Klark | 11/30/2011

" This books has an action sequence beginning on page 1. Very entertaining read and one of my favorites by Ludlum. Those that like the Bourne series would enjoy this book. "

Kris | 6/26/2011

" A large part of the story takes place in Switzerland and Austria, they spend some time in Zurich so it was interesting to read about places we have been, I also liked being able to read all the German phrases. It's also an interesting plot with likeable characters. "

Jim | 4/25/2011

" Fast-paced action. I have always liked Ludlum's style, and this met expectations. It was hard to put down once started.
"

Audrey | 2/22/2011

" This was a great break after the more thought provoking books. Just a good mystery novel that reads fast.
"

George | 12/19/2010

" battle of morals gone horribly right.
"

Shrikant | 12/19/2010

" A fine book carrying a good, well thought out and detailed plot and narration. A real time, action-packed adventure.
"

Dhiratara | 11/22/2010

" This book is older than Da Vinci Code and all rows of Dan Brown's work. But I suggest you to read this after you learn the basic subject of conspiracy thingy in Da Vinci Code, Angels and Demons, The Holy Grail, etc. It's shocking, electrifying, mesmerizing!
"

Mike | 11/22/2010

" Not the best of Ludlum"s books.
In fact... It's kind of cheezy.
"

Jelan | 9/13/2010

" This is a typical, enjoyable Ludlum book... an escapist page-turner. The premise was fairly far-fetched, but I enjoyed every page nonetheless. I'm always happy to discover a Ludlum I haven't read yet when I'm in need of a mental break.
"

Shauna | 8/24/2010

" Great book. Very suspensful. I like books like this. I think I will read more of Ludlum's books. I did read the Bourne series and I loved those.
"

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